Hill-Start of Distributed Drive Electric Vehicle Based on Pneumatic Electronic Parking Brake System

The hill-start assist system (HAS) ensures that the vehicle starting on the ramp will not roll backwards, which improves the convenience of the driving in the case of starting on the ramp and parking. However, the traditional hill-start method is not suitable for distributed driving electric vehicles under some circumstances. Therefore, based on the pneumatic electronic parking brake system (EPB), a hill-start control method suitable for distributed driving electric vehicles is proposed in this paper, so as to realize the vehicle's fast and stable starting on the ramp. Firstly, by analyzing the change of the force of the vehicle during the starting of the ramp, a dynamic allocation strategy based on the front and rear axle loads is adopted in terms of demand torque. Secondly, according to the force analysis of the vehicle on the ramp, the control target of hill-start is determined, and the logic threshold control method is used to make the actual pressure change with the ideal pressure in real time. Then, a driving torque correction controller based on the sliding mode algorithm is designed to prevent driving wheels from slipping on bad roads, resulting in a reduction in the total driving force and a rollback of the vehicle. Finally, to verify its feasibility, Matlab, Trucksim and AMEsim were used to establish the controller model, the vehicle model and the pneumatic EPB system model for co-simulation verification. The simulation results show that the proposed control strategy can prevent the vehicle from slipping under different road conditions with less brake wear.